The present invention pertains to a rotating oculus window in a split-sphere observatory dome. The split-sphere observatory dome may be of the type described in U.S. Pat. No. 4,840,458 to Ethan W. Cliffton (issued Jun. 20, 1989), the disclosure of which is hereby incorporated by reference in its entirety. Such a dome may be used, for example, to house a telescope, satellite tracking equipment, or any other equipment requiring an oculus.
Observatory domes which are, for example, adapted to be utilized for astronomical purposes are generally of a hemispherical configuration and have been provided with an aperture of generally rectangular configuration running longitudinally from the area of the apex of the dome (zenith or vertical axis) downwardly to the vicinity of the equatorial region of the dome (horizontal axis) so as to facilitate the aiming or sighting of a telescope or the like there through.
A dome of the nature described is generally provided with a weather-tight shutter assembly adapted to permit selective opening and closing of the sighting aperture. The shutters utilized are normally fabricated from sheet metal and are characterized by a generally elongated rectangular, longitudinally curved, or convex configuration and are mounted exteriorly of the dome so as to be adapted to uncover the sighting aperture by upward movement of the shutters on a plane tangentially disposed with respect to the curvature of the dome.
It is important that the telescope or other equipment usually housed within such domes be properly protected from the entrance of moisture into the dome. One problem with conventional domes results from the fact that under present practice the shutters do not provide a completely water-tight closure in the normal closed position. Thus, water may enter the interior of the dome and thereby cause considerable damage to the instruments within the dome.
Conventional observatory domes of the type described above suffer from a number of other problems which are primarily attributable to the use of shutters as described above. In particular, in conventional observatory domes large openings are not possible without limiting horizon viewing with conventional shutters and wind screens. Moreover, the concentric protrusions common to conventional shutter design increase wind load and cavitational icing. Further, conventional domes require massive arch girders and eccentric ring girders to resist bending and spreading of the slot. Finally, the provision of moveable shutters hinders the weather resistance of the dome as discussed above.
A split-sphere dome with a fixed shutter obviates the above-described disadvantages experienced in conventional observatory domes. A split-sphere dome such as the one disclosed in U.S. Pat. No. 4,840,458 is an improvement over conventional telescope domes, which provided a vertical open slit to allow the telescope to view the sky. The conventional dome was essentially designed for astronomy and therefore, the oculus was an open slit in the dome wall through which air could move in and out, and the telescope was located in the center. By providing a fixed shutter in a split-sphere dome, the weather resistance of the dome may be increased and the size of the opening (oculus) may be increased, as well as other advantages that may be achieved with this design. One advantage of the split-sphere design is the ability to mount a fixed window in a dome as an oculus. Rather than having simply a hole in the dome open to the atmosphere when the shutter is open, this design may seal the dome to the atmosphere. For example, in a dome designed according to U.S. Pat. No. 4,840,458, a temperate, clean-room environment for, for example, a laser telescope or a lidar (infrared laser) device may be provided. The window shields the telescope (or other housed device) from contact with the outside atmosphere and makes it possible to control the interior environment (e.g. heating and cooling) of the dome. An example of a dome with a fixed window was built by Electro Optic Systems, Queanbeyan, NSW, Australia.
As a telescope or other housed device moves (e.g., pivots about an axis) to track an object or location across the sky, the oculus moves with it. In certain applications where the oculus includes a window, orientation of the window to the housed device may be required to remain fixed, even where the device moves to track an object across the sky. For example, where there are multiple devices looking through multiple sections of subsections of the window, or where the window is polarized, the orientation of the window to the housed device(s) may be required to be constant.